Since this part of the thread began, I've gradually been coming to a new realization about these forms. Partly it was the reaction of people to using -masta for a whole and definite action like the operation in question. Partly it was that paragraph or two at the end of VISK § 931 comparing -massa to -essa.jahasjahas wrote: I tried to come up with a guideline on when the construction "palasivat tekemästä" works and when it doesn't, but failed. Is it semantic or grammatical? All I can say is that "Sotilaat palasivat ampumasta sorsia." sounds much better than "Sotilaat palasivat ampumasta bin Ladenin.".
I suppose on some level, the two prototypes for me have always been käymässä and ostamassa. The first is pretty clearly an activity with no particular completion. You just do it for a while and then stop doing it. I've thought of the second has having a purpose and a point of completion.
But now I'm getting the impression that -massa is sort of the "normal form" and the emphasis is on being in the midst of any process. And -maan and -masta are about entering and leaving (not completing) such a non-terminal process. So even though VISK says that -massa can take a total object if something gets completed, that now seems to be like an exception to the general conceptualization. So to a Finn, it feels more natural to return from "hunting around for ducks" than it does to return from shooting one duck. Palata ostamasta is to return from being in the process of shopping for something, not so much to return from having bought something. (Yes, I know there's a different verb to emphasize shopping rather than buying.) But inevitably people (like me) start to hear a construct that really means one thing as interchangeable with one that means something similar. The subtleties erode. Cf Näin Leenan nukkuvan and Näin Leenaa nukkumassa earlier in this thread and two responses further down. Thus some people are more bothered than others about -masta used to describe having completed an action.
Or something like that.
"Right now its only a notion. But I think I can get money to make into a concept and later turn it into an idea."